The production of P(AS) for a variety of industrial and commercial uses has been known for some time. P(AS) is moldable into various articles including, but not limited to, parts, films, and fibers by means of, for example, injection molding and extrusion molding techniques. These articles have utility in a variety of applications where heat and chemical resistance properties are desired. For example, P(AS) can be utilized as a material for preparing electrical and electronic parts and automotive parts.
Generally, P(AS) is prepared by contacting reactants comprising at least one dihalogenated aromatic compound, at least one POC, at least one sulfur source, and at least one base under polymerization reaction conditions. Molecular weight modifier compounds can be added to produce high molecular weight P(AS). The most preferred modifier compound is sodium acetate due to its availability and effectiveness.
There are several problems associated with the current synthesis of P(AS) that cause the production expenses to be high. First, in both quench and flash P(AS) processes, modifiers utilized to synthesize the high molecular weight P(AS) are used once in the process and are not captured and recycled for subsequent use. This constitutes a great expense in the production of P(AS) due to the higher feedstock and waste disposal expense. Secondly, POC utilized in the process can be recovered, but often at a high cost. For example, n-hexanol is often utilized to extract N-methyl-2-pyrrolidone (NMP), a common POC. Operating the hexanol extractor system can require the handling of as much as 30 to 40 pounds of n-hexanol per pound of P(AS) produced causing high equipment and operational costs.
There is a need in the P(AS) industry for an efficient process to recover the modifier compound and POC from various streams. This invention provides such a process.